US 3616867 A
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United States Patent 1 1 3,616,867
 Inventor Alfredo Celli  References Cited Via Senio, Forli, Italy UNITED STATES PATENTS [211 1 3 1: 1970 2,621,463 12/1952 Skillman...... 56/2X 22 g" d 1 2,845,050 7/1958 Wacker e161 173/170x 1 F E F 3 1969 3,012,441 12/1961 Lambetal... 173/163X g 3,156,231 10/1964 Harding 173/17ox  51876 A/69; Primary Examiner-David H. Brown A 11, 1970, It l No. 68229 A/70 Attorney-Sughrue, Rothwell, Mion, Zinn & Macpeak ABSTRACT: A motor unit for driving a machine or tool such as a gardening tool has small stroke internal combustion en-  FOR GARDEN APPLIANCES AND gine mounted on a tubular frame which has provision for attachment of an extension handle-for example, when using 6 Claims 11 Drawing Figs the unit to power a lawnmower. The engine is coupled to an  US. Cl 173/163, output shaft for power takeoff to the machine or tool by way 173/170 of transmission means including a speed reducer which is  lnt.Cl B27c 3/08 selectively engageable. The tubular frame is provided with  Field of Search 173/163, rapid attachment means for connection of the motor unit to 170, 171; 77/7; 143/1; 30/122; 56/2 the machine or tool to be driven.
PATENTED V 2 l9?! SHEET 2 OF 4 PATENTEUunv 2 lSTl SHEET 3 [1F 4 PAIENTEUHUV 2 I971 3,616,867
SHEET '4 OF 4 Fig. 8
POWER UNIT FOR GARDEN APPLIANCES AND THE LIKE This invention relates to motor units for operating horticultural or agricultural machines or tools.
Motor units for this purpose are known which comprise an internal combustion engine and means for attachment of the unit to a machine or tool to be operated by the engine.
In general, however, such known units are cumbersome and heavy, and this presents an obstacle to the extensive practical use of such units, especially where the tool or machine to be operated is of the type designed to be held in the hand.
Moreover, such known motor units generally have a single speed of operation, and this limits their range of application to particular types of tools or machines. In order to extend the range of operation of such units to lower speed tools it is necessary to modify them by fitting appropriate speed reducers, or to fit speed reducers to the tools or machines to be driven.
An object of the present invention is to provide a motor unit of the aforementioned type of relatively reduced size and weight, which is of simple and strong construction and practical and easy to use.
A further object of the invention is to provide a motor unit of the said type which is capable of rapid attachment to different tools or machines to be driven.
According to the invention there is provided a motor unit of the aforesaid type, characterized in that the internal combustion engine has a small piston stroke and is mounted on a tubular support provided with an upper handle and with an attachment for an extension handle, the said engine being coupled, through selectively engageable speed reducer means, to an output shaft adapted for power takeoff to the machine or tool, the said tubular support being provided with rapid attachment means for connection of the motor unit to the said machine or tool to be operated thereby.
The motor unit according to the invention can be used to motorize a wide range of different tools or machines having different operating speeds.
The invention will now be described, by way of nonlimiting example, with reference to the accompanying drawings, in which:
FIG. I is a side elevation of a motor unit according to a preferred embodiment of the invention, shown in a state of detachment from cooperating parts of a tool to be driven thereby;
FIG. 2 is a diagrammatic transverse cross section taken along the line II-Il of FIG. 1;
FIG. 3 is a diagrammatic plan view, partly cut away, of the motor unit of FIG. 1;
FIG. 4 is a partial section of the motor unit taken in the vertical plane represented by the line IV-IV in FIG. 3;
FIG. 5 is an axial section of one-half of the speed reducer incorporated in the motor unit of FIG. 1, sectioned along line V-V of FIG. 3, and showing a first setting of the speed reducer in which the latter is operative;
FIG. 6 is an axial section similar to FIG. 5, showing the speed reducer in a second setting in which it is inoperative, and
FIGS. 7 to ill inclusive are diagrammatic plan views showing some examples of practical applications of the motor unit of the invention.
As shown in FIG. I the motor unit 1 according to the invention has a shaped tubular metal support frame 2 upon which is mounted an internal combustion engine 9 of small piston displacement. The tubular frame 2 has a lower horizontal portion 24 upon which the engine 9 is mounted by means of a front fixing lug 6 and a rear lug 8, the latter being bolted to a rear support plate 7 which is in turn bolted to the rear of the engine 9. The tubular frame 2 also includes an upper horizontal portion 2b upon the end of which a handgrip 3 is affixed, and, branching from the lower portion 2a an upwardly inclined rear tubular attachment 4 to which a rear tubular extension handle 5 may be fitted in use of the motor unit (FIGS. 7 to l l A fuel tank 53 for supplying fuel to the engine 9 is slung beneath the upper frame portion 2b.
The engine 9 is provided with a centrifugal clutch 10 (FIGS. 3 and 4) which drives a toothed pulley Ill. A flexible toothed transmission belt 12 provides a drive connection between the pulley 11 and a similar toothed pulley l3 keyed to one end of an intennediate shaft 14.
The shaft 14 is rotatably and coaxially supported in a tubular casing 15 which is attached to the cylinder block of the engine 9 by means of intermediate lugs 16. The tubular casing 15 is closed at one end by a cap 17 in which a bearing for the shaft 14 is supported. At its other end the casing 15 is closed by a tapered head 18 having a central axial opening through which an output shaft 19 projects. The shaft 19 is driven by the intermediate shaft 14 and affords a power takeoff point for operating tools or machines adapted to be driven by the motor unit 1.
One-half of the casing 15 is shown in axial section in FIGS. 5 and 6. The casing 15 houses a speed reducer which can be engaged as required to drive the output shaft 19 with a reduced rotational speed in relation to that of the intermediate shaft 14. When the speed reducer is not engaged the output shaft 19 is driven at the same rotational speed as the intermediate shaft 14.
The intennediate shaft 14 has an axially splined end within the casing 15 in permanent meshing engagement with a group of toothed planet wheels 20. The wheels 20 rotate in planetary motion around the inside of an internally toothed fixed ring gear 21, the planet wheels 20 being rotatably mounted on respective pins 22 which are carried by a rotary planet carrier. The planet carrier comprises a front plate 23 and a rear plate 24, the latter having a tubular rearward extension 25 projecting axially towards the head 18. The tubular extension 25 is provided at its extremity with internal gear teeth 26.
The output shaft 19 is spaced from but coaxial with the intermediate shaft 14. The shaft 19 has an axially splined inner end 19a within the casing 15, matching the adjoining splined end 14a of the shaft 14. A tubular sleeve 27 is mounted for axial sliding movement on the splined shaft end 190, being for this purpose formed with internal axial splines 29 mating with the splined end 19a. The sleeve 27 has an external row of gear teeth 28 which, in a first axial position of the sleeve 27 (FIG. 5) meshes with the internal gear teeth 26 of the planet carrier extension 25.
In a second axial position of the sleeve 27 (FIG. 6) the internal splines 29 of the sleeve 27 engage the externally splined and 14a of the intermediate shaft 14, drivingly interconnecting the shafts 14 and 19.
The tubular sleeve 27 is provided at its end opposite the teeth 28 with a pair of annular flanges 30 defining between them an annular channel in which one end of a selector lever 31 engages. The selector lever 31 is formed integrally with a radial crankpin 32 which is rotatably supported in and projects outwardly from an internal boss 33 on the head 18. A selector control lever 34 is attached to the outwardly projecting end of the pin 32: appropriate rocking movement of the lever 34 causes axial movement of the sleeve 27 between its first and second positions In the first operative position of the sleeve 27 (FIG. 5) the teeth 28 are engaged with the teeth 26 of the planet carrier extension 25, while the internal splines 29' of the sleeve are engaged only with the splined end 19a of the output shaft I9. Under these conditions, drive is transmittedifrom the shaft 14 to the output shaft 19 at reduced speed via the planet wheels 20, the planet carrier 23, 24 and the sleeve 27.
In the second position of the sleeve 27 (FIG. 6) the splined ends 14a and 19a of the respective shafts 14 and 19 are directly interconnected by their engagement with the internal splines 29 of the sleeve 27, the latter having been moved to the left from the position shown in FIG. 5 to span the adjoining coaxial splined ends 14a, 19a. The external teeth 28 of the sleeve 27 are disengaged from the internal teeth 26 of the extension 25 of the planet carrier, and the shaft 14 transmits drive direct to the output shaft 19 without any change of speed.
It is therefore possible to engage or disengage the speed reducer simply by manipulation of the control lever 34. This simplifies the construction of the motor unit 1 and simplifies the use of the unit, since assembly and disassembly of a speed reducer separate from the motor unit, as has previously been necessary, is avoided.
The lower portion 2a of the tubular support frame 2 is provided with means for the rapid attachment of the motor unit 1 to a tool or machine to be driven. Such attachment means, shown in FIGS. 1 and 2, comprise a hook 40 arranged beneath the frame portion 2a adjacent the mounting lug 6 and a clamping pin 41 extending through the frame portion 2a and mounted therein for rotation about a lateral horizontal axis spaced from the hook 40. The pin 51 is provided at one end with an adjuster nut 42 and at the other end with an axially slidable clamping member 43 with which a lever arm 44 cooperates. The lever arm 44 is integral with an internal eccentric cam (not shown) which is effective to displace the clamping member 43 along the pin 41 selectively towards or away from the nut 42 when the lever arm 44 is rocked through 90 The above-described attachment means cooperate with corresponding attachment means on the tool or machine to be connected to the motor unit 1. Part of a transverse support of the tool is shown at 35: a plate 36 is mounted on the upper side of the support 35 and has an outwardly projecting edge 37 adapted to engage in the hook 40 of the motor unit frame portion 20. A forked cradle member 36 is mounted on the plate 36 and is adapted to receive part of the tubular frame portion 2a. The upwardly projecting arms of the forked cradle member 38 are formed with an aligned pair of vertical slots 39, open at their upper ends, into which the outwardly projecting parts of the said transverse pin 41, inwardly of the nut 42 and the clamping member 43 may be engaged.
To connect the motor unit 1 to the tool to be driven, it is simply necessary first to engage the projecting edge 37 of the plate 36 in the hook 40 and thereafter to locate the tubular frame portion 2a in the cradle member 38 with the ends of the pin 41 engaged in the slots 39. The lever arm 44 is then rotated through 90 to the position shown in broken outline in FIG. 2 to clamp the forked arms of the cradle member 38 between the frame portion 2a and the nut 42 and clamping member 43 respectively.
Disengagement of the tool from the motor unit 1 is effected by reversing the operations described above.
The motor unit I as described can be used for driving tools and various agricultural and horticultural machines, some of which are illustrated in H68. 7 to 11.
ln FIG. 7, the motor unit 1, fitted with the extension handle 5, is directly connected to a rotary hoe having radial blades, adapted to be held in the hand by means of the extension handle 5.
In FIG. 8 the motor unit I is connected to a lawn mower or rotary grass cutter 46 supported on the ground by means of wheels or rollers. The output shaft 19 is fitted with a toothed sprocket for driving the rotary grass cutter by means of a chain transmission 19 The mower 46 is guided by means of the extension handle 5.
FIG. 9 illustrates the mounting of the motor unit 1 on a wheeled carriage 47 which carries a pump 68, directly connected to the output shaft 19 of the motor unit 1. The pump 48 is connected to a liquid spray and draws liquid from a storage tank 49 on the carriage 47.
FIG. shows an arrangement similar to that of FIG. 9, in which the motor unit 1 is mounted on a wheeled carriage 47. In this case the motor unit 1 drives a centrifugal pump 50 which is driven at high speed by appropriately presetting the speed reducer of the motor unit to achieve maximum output shaft speed.
A further application is illustrated in FIG. 11, in which the motor unit 1 is again mounted on a wheeled carriage 47. However, the output shaft 19 of the motor unit 1 is in this example connected to a powered hedge trimmer 52 having a rotary drive input, by way of a flexible drive transmission 51.
It will be understood that, in addition to those applications specifically described by way of example, the motor unit according to the invention is capable of numerous other applications where a machine or tool to be driven is provided with means for attachment of the motor unit and means for coupling the drive output of the motor unit to the machine or tool.
What is claimed is:
1. Motor unit for operating a horticultural or agricultural machine or tool, comprising an internal combustion engine and means for attachment of the unit to a machine or tool to be operated by said engine, wherein the improvement consists m:
i. a tubular support upon which the internal combustion engine having piston stroke, is mounted;
ii. an upper handle (3) and an attachment for an extension handle carried by the said support;
iii. an output shaft for power takeoff to a machine or tool to be operated;
iv. transmission means through which the engine is coupled to the output shaft;
v. speed reducer means;
vi. selector means for selectively inserting the speed reducer means in said transmission means, and
vii. rapid attachment means on the tubular support for connection of the motor unit to the said machine or tool to be operated thereby.
2. Motor unit as claimed in claim 1, wherein the said transmission means include a centrifugal clutch and a toothed belt drive transmission coupling the internal combustion engine to the speed reducer means.
3. Motor unit as claimed in claim 1, wherein the rapid attachment means for the connection of a machine or tool to the motor unit comprise a hook provided on a lower portion of the tubular support and adapted to engage a projecting edge of a support plate affixed to the machine or tool, and a clamping pin extending laterally through the said lower portion of the tubular support and provided with opposed clamping elements adapted to clamp respective arms of a forked member attached to or integral with said support plate of the machine or tool, which arms have respective slots in which the said clamping pin engages.
4. Motor unit as claimed in claim 1, wherein the speed reducer means comprise;
i. a tubular casing attached to the engine;
ii. an intermediate shaft extending coaxially into the said casing and drivingly connected to the engine;
iii. external splines on one end of the said shaft within the casing iv. a planet carrier rotatably mounted within the casing;
v. toothed planet wheels rotatably mounted on the planet carrier, said planet wheels being in constant mesh with the external splines on said shaft;
vi. a fixed internally toothed ring gear meshing with the said planet wheels;
vii. a tubular extension of the planet carrier, said extension having internal gear teeth;
viii. an externally splined end of the said output shaft within the casing and coaxial with the intermediate shaft;
and wherein the said selector means are effective in one position to interconnect the said end of the output shaft with the planet carrier extension and in another position to connect the output shaft directly with the intermediate shaft, whereby the output shaft may be driven from the intermediate shaft at two different rotational speeds.
5. Motor unit as claimed in claim 4, wherein the said selector means comprise an axially slidable tubular sleeve mounted coaxially on and coupled to the said splined end of the output shaft (19), the said sleeve having external gear teeth which in a first axial position of the sleeve cooperate with the internal gear teeth of the planet carrier extension, said external gear teeth in a second axial position of the sleeve meshing with the external splines of the said intermediate shaft, whereby in the first position of the sleeve the output shaft is driven at a different speed from the intermediate shaft by way of the planet gears and planet carrier, and in the second position of the sleeve the output shaft is directly driven from the intermediate